I believe that many Mac users are as much concerned about the disk usage of Mac computers as the small series. When the reading speed slows down, you have to look at the disk space. If you find that you are taking up a lot of space, you have to clean up your Mac's system disk.
One, view Mac system disk space
1. Look at the "other" section size in OS X, click on the top Apple menu and select "About this Mac".
Figure 1: View Mac disk storage information
2. Then select the "Storage" tab in the middle of the window. You can find the disk space distribution of your Mac computer, and the "Other" section (blue) is relatively small.
Picture 2:mac disk storage information
Note: OS X identifies centralized file types such as application, backup, audio, movie, backup, and photo, while the "other" section contains quite a few file types. To get rid of this rubbish, you have to clean it up with Mac cleanup software--cleanmymac.
Second, Cleanmymac clean Mac system disk
1. Open Cleanmymac, click "Smart Cleanup", then click Scan.
Figure 3: Click on smart Cleanup
2, when the scan is completed, will be prompted how much garbage, click on the cleanup button below, began to clean the computer.
Figure 4: Scan complete
3. After the cleanup is complete, the prompt to complete the cleanup will appear.
Figure 5: Disk Cleanup complete
When the disk is cleaned up, the speed of the computer will naturally increase. Download Cleanmymac, you don't have to watch the computer running slowly, and you are helpless.
See Cleanmymac How to clean up Mac system disk